Right-click the plot name in the COSMOS AnalysisManager tree and select Chart Options.
In the PropertyManager, select the desired position, format, and color options.
Click 
.
You can set the font, relative position of the legend, width of the color bar, number format, number of decimals, and background color.
To customize the font for all plots:
Right-click the study name in the COSMOS AnalysisManager tree and select Options.
On the System Options tab, select General in the tree.
Under Font, click Plot Title, Plot Subtitle, and Legend to select a font.
Click OK.
To customize the legend for new plots:
Right-click the study icon in the COSMOS AnalysisManager tree and select Options.
On the Default Options tab, select Color Chart in the tree.
Select the desired position, width, number format, and color options.
Click OK.
To customize the legend for existing plots:
Right-click the plot name in the COSMOS AnalysisManager tree and select Chart Options.
In the PropertyManager, select the desired position, format, and color options.
Click .